This invention relates to catheterization of a patient, and more particularly to the control thereof so that the catheter may be used for a long period of time without the need for the usual and customary administration and maintenance of saline and heparin locks. More particularly, this invention relates to an obturator device which controls the lumen of the catheter, selectively, to allow spaced intervals of feeding and non-feeding of fluids through the catheter to the patient while the same catheter and the associated obturator remain in place, and under continuous sterile conditions.
The obturator of the invention may be fed selectively to occlude the catheter lumen and then may be withdrawn to a position allowing fluid delivery through the catheter to the patient. Thereafter, the same obturator may be fed forward to occlude the lumen again until such time as the next fluid delivery is required. With such an arrangement, the same catheter-obturator assembly may be used for periods as long as seventy-two (72) hours, for example.
For many applications, a catheter, after insertion into a patient may be maintained in place for periods up to two weeks or more. During this time, the medication changeovers may be alternated with periods when no solutions are being administered to the patient. It is essential that patency of the catheter be maintained during the changeover and non fluid administration periods.
As will be understood by practitioners in the art, patency of vascular access catheters, with or without an attached intravenous drip, are generally maintained in one of three ways. First, a sterile aliquot of heparin solution may be injected into the catheter. This method, often termed a heparin lock or flush, is costly since expensive heparin is required for long periods. Secondly, a sterile bolus may be used of normal saline solution injected into the catheter as an alternative to the heparin application. Both of these methods are done routinely and often. They have certain limitations, however, because of normal diffusion at the tip of the catheter, blood may replace infused heparin or saline solution with the result being loss of patency through the formation of a clot near the tip of the catheter.
Finally, maintenance of patency may be maintained by the use of a stainless steel or plastic obturator inserted loosely inside the catheter and attached with a luer connector. These devices are somewhat primitive, and do not completely seal the catheter so that blood may seep back into the space between the catheter and the obturator. This backflow of blood not only may clot and occlude the catheter or interfere with subsequent removal thereof, but also is an excellent breeding ground for infection.
With this invention, by contrast, a device is provided in the form of an elongated obturator comprised of a rod of semi-flexible material which may be fed through the use of, alternatively, a push rod arrangement or a reel feed arrangement to allow feeding of a sterile obturator into and through the lumen of an in-place catheter. In this connection, this invention is related to the invention taught and claimed in co-pending application Ser. No. 369,430, filed June 21, 1989 which is hereby incorporated by reference in its entirety.
That is, the invention claimed in that co-pending application describes and claims an obturator arrangement with a specific coating on the surface thereof for providing the proper degree of swelling necessary for an obturator as utilized in the device of this invention so as to seal completely the lumen of the catheter once the obturator is in place in its sealing position. Thus, the elongated slightly flexible obturator rod of the invention here utilizes on the surface thereof a coating comprised of a hydrophilic polyetherurethane capable of absorbing liquid and increasing the diameter of the obturator. Moreover, the coating includes an anti-thrombogenic and/or anti-infective agent bulk distributed in the polyetherurethane material. That is, the agents, whether anti-thrombogenic or anti-infective or both, are distributed throughout the polyetherurethane so that there is a slow release of these agents during use of the obturator of the invention.
When the obturator of the invention is fed forward into its sealing position in the lumen of the in-place catheter, it is wetted by an aqueous liquid such as blood, for example. The hydrophilic polyetherurethane absorbs the blood or other aqueous liquid causing it to expand so that the obturator overall dimension increases in diameter and contacts the lumen wall of the catheter to form a seal. Moreover, during this expansion, the anti-thrombogenic and/or anti-infective agent is slowly released in order to avoid infection and/or blood clotting.
Thereafter, the user may, with the device of the invention, withdraw the obturator from a position occluding the catheter lumen completely to a withdrawn position wherein a fluid delivery entry may be made into the catheter lumen for administering a fluid to a patient. Subsequently, in accordance with this invention, once the fluid has been delivered in the quantity desired, the fluid delivery outlet to the lumen may be stoppered and the same obturator, in accordance with this invention, may be fed forward again to reseal the catheter lumen until the next fluid delivery is to be made.
In considering generally the conditions for carrying out the invention here, the basic rod material upon which the hydrophilic polyetherurethane is coated may be any substantially non-hydrophilic material which, when extruded, is of sufficient stiffness in order to provide the control necessary during its use while being sufficiently flexible in order to be maneuvered, as will be discussed in more detail below. Suitable materials are, for example, metal, such as stainless steel, or preferably, a polymer. Preferred polymers for the rod are the polyolefins, such as polyethylene or polypropylene, and polytetrafluoroethylene, polyester, polyamide, polyurethane, polystyrene, polyvinyl chloride and liquid crystal polymers.
In the past, arrangements have been provided wherein catheters themselves have included a feeding device for moving the catheter in place. Moreover, insertion catheters have utilized controls for feeding a separate needle for actual insertion through the skin of the patient which needle is withdrawn from any further use once the catheter is in place. For example, U.S. Pat. No. 3,734,095 teaches placement of a stylet needle within a catheter prior to venipuncture and removal of the needle after the venipuncture. The device described deals with controlled insertion and withdrawal of the stylet. However, the system does not have any moveable parts. The system of the invention discloses a method of removal of the needle without exposing the luer of the catheter to air and/or contaminants with accessories. U.S. Pat. Nos. 3,313,299 and 3,727,613 also teach devices of this kind.
U.S. Pat. No. 3,835,854 teaches a device which feeds the catheter through the vein, as discussed above. The device uses friction to propel the catheter into the vein. U.S. Pat. No. 3,838,688 also uses a friction type of arrangement of this kind. By contrast with the invention here, the obturator rod is anchored, in one embodiment, to a reel acting as a cam which is then used to insert or withdraw the obturator rod, as required into the attached catheter.
Other U.S. patents teach inventions which insert a catheter into the vein of a patient by a pressure mechanism. This kind of device is taught in U.S. Pat. Nos. 4,159,022; 4,243,033; 3,703,174 and 3,826,256.
U.S. Pat. No. 4,160,451 uses a mechanism, also, for feeding a catheter into place in the vein of a patient. The point of the invention taught in this patent is to place the catheter so that it cannot be accidentally retracted.
With this invention by contrast, an obturator rod is fed into the already in place catheter for the purposes of occluding the lumen of the catheter, as desired, without having to use the conventional expensive and cumbersome procedures of heparin or saline locks. Moreover, the device of the invention is sterile when placed in use and remains sterile during the entire use procedure. In addition, the obturator rod when placed in its sealing position, seals effectively the lumen of the catheter from any blood leakage. It avoids contamination of any kind and any blood clotting because of the presence of the heparin and/or anti-infective agent in the swellable material coating the rod.
Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings, and the appended claims.